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Homework Help: Need help on driving question. Please Help

  1. Oct 3, 2013 #1
    A person is driving a car down a road. The instantaneous acceleration is increasing with time, but is directed opposite the direction of the car's motion. what is the speed of the car? is it decreasing because the acceleration is opposite with the car's motion? Please Help. Thank you
  2. jcsd
  3. Oct 3, 2013 #2
    Acceleration is change in velocity over time, so if it is in the opposite direction to the cars motion, then the acceleration would be negative.

    If you had a negative acceleration, what would you expect to happen to the velocity as time went on?
  4. Oct 3, 2013 #3


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    Science Advisor

    The statement is a little vague. Is the acceleration directed opposite of the car's motion, or is the increase in the acceleration directed opposite of the car's motion?
  5. Oct 4, 2013 #4
    The instantaneous acceleration in increasing, it's not constantly increasing and it's opposite direction of the car's motion. So I thought that the speed is decreasing since the acceleration is opposite with the car's motion.
  6. Oct 4, 2013 #5


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    Staff: Mentor

    That's sound reasoning. Sometimes the hardest part of a problem lies in interpreting the wording :smile:

    The situation described is analogous to stepping on the brakes with increasing force (while the car is in motion, of course).

    P.S. chrissy9624, next time please make use of the posting template provided when you start a thread. Homework Help posts need to meet a certain format, content, and effort level. You barely met the last two criteria with the above :smile:
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